/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/************************************************************************
 * kernel/task/task_getpid.c
 *
 *   Copyright (C) 2007, 2009, 2014 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ************************************************************************/

/************************************************************************
 * Included Files
 ************************************************************************/

#include <sys/types.h>
#include <unistd.h>
#include <sched.h>

#include "sched/sched.h"
#include "task/task.h"

/************************************************************************
 * Pre-processor Definitions
 ************************************************************************/

/************************************************************************
 * Private Type Declarations
 ************************************************************************/

/************************************************************************
 * Global Variables
 ************************************************************************/

/************************************************************************
 * Private Variables
 ************************************************************************/

/************************************************************************
 * Private Function Prototypes
 ************************************************************************/

/************************************************************************
 * Public Functions
 ************************************************************************/

/************************************************************************
 * Name: getpid
 *
 * Description:
 *   Get the task ID of the currently executing task.
 *
 ************************************************************************/

pid_t getpid(void)
{
	FAR struct tcb_s *rtcb;

	/* Get the TCB at the head of the ready-to-run task list.  That
	 * will be the currently executing task.  There is an exception to
	 * this:  Verify early in the start-up sequence, the g_readytorun
	 * list may be empty!  This case, of course, the start-up/IDLE thread
	 * with pid == 0 must be running.
	 */

	rtcb = this_task();
	if (rtcb) {
		/* Return the task ID from the TCB at the head of the ready-to-run
		 * task list
		 */

		return rtcb->pid;
	}

	/* We must have been called earlier in the start up sequence from the
	 * start-up/IDLE thread before the g_readytorun list has been initialized.
	 */

	return 0;
}
